Adds Miri to CI/CD #311

Job	Run time
docs/stable	22s
cargo-careful	1m 55s
cross_test/s390x-unknown-linux-gnu/stable	4m 48s
clippy/stable	18s
cross_test/i686-unknown-linux-gnu/stable	1m 26s
format/nightly	12s
nostd/thumbv6m-none-eabi/stable	15s
tests/stable	2m 43s
miri	1h 0m 30s
tests/beta	3m 10s
tests/nightly	3m 11s
tests/1.64.0	3m 49s
conclusion	1s
	1h 22m 40s

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